Navigators make sure debris will have it tough in Camp Creek flood
The construction of two Queen's Canyon-spanning “debris racks” is nearing completion in the Camp Creek drainage above Glen Eyrie.
Formed of interlocking rings and posts, the large metal structures will absorb the impact of trees or boulders in a flood, protecting downstream residents and properties, according to Derek Strickler, Glen Eyrie director of operations. “They should protect Pleasant Valley as well as Rock Ledge Ranch and the Garden of the Gods,” he said.
The $616,000 cost is being funded by a federal grant (75 percent) and by the Navigators (25 percent). The nonprofit Christian organization, which has owned Glen Eyrie for about 60 years, had to fundraise its roughly $150,000 share, Strickler said.
Also called debris “fences” or “nets,” the racks were deemed necessary following the Waldo Canyon Fire, by engineers alarmed at the loss of vegetation that formerly slowed or absorbed rainfall runoff into the upper reaches of Camp Creek.
The plan is for the racks to stop large debris, preventing disastrous impacts downstream. Water will get through, but the build-up behind each rack will help reduce velocity, Strickler said. The upper rack was finalized this week, with the lower one under way and scheduled to be done before spring rains start.
Part of the design involves a pivot at the base of the metal posts in the middle of each rack, allowing the structure to “give” somewhat if it's struck by fast-moving or extremely heavy objects. The rings also have some flexibility, he noted.
Asked how much weight a rack can handle, Strickler replied that he did not have that specification but it's safe to say the racks “are overengineered. They're designed for catastrophic hits.”
Both racks are 21 feet high, bolted in numerous places into the walls on the sides of the canyon. The upper rack, completed this week, is 69 feet wide at the top and 49 feet wide at the bottom. The lower rack, still under construction, will be 83 feet at the top and 40 feet at the bottom, Strickler said.
Including less gargantuan projects - such as armoring the banks of the creek where it passes the Glen Eyrie castle of Colorado Springs founder William Palmer - Strickler estimated that the Navigators are spending about $1 million overall on post-Waldo flood mitigation.
The rack locations are about a quarter-mile apart, with the lower one a short distance upstream from the castle. The upper rack is just below the boundary with the National Forest Service property and just above a system of pipes and pumps - dating back to Palmer's time - that diverts some Navigator-owned water from the creek to the Colorado Springs Utilities system.
That diversion, which provides a certain cash flow to the Navigators, could become another casualty if future floods prove to be as scary as predicted. A not-unlikely eventuality, as described by Strickler, would be such a massive build-up behind the upper rack that it would have to be cut away, resulting in the diversion being buried beneath piles of rocks.
Another expected result of cutting away the upper rack would be the debris washing down to the lower rack. It is designed a little differently. Because of the canyon's width there, one side is being built up with gabion baskets to allow a utility road alongside. This will allow excavating equipment to set up beside the rack and remove debris after large storms.
The thinking is that after 10 years neither rack may be needed. That's about how long specialists believe it will take for enough vegetation to grow back in the burn area so that the drainage will behave like it did before, Strickler said.
Local officials have talked to the Forest Service about placing a debris rack upstream, on its part of the Camp Creek drainage and closer to the burn areas, to slow the force of a major flood before it gets to the Navigator segment. However, no such plan is yet in the works.
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